High-Temperature Labels: What Survives Reflow Soldering?
Labels on printed circuit boards have to survive reflow soldering up to 260 °C, the wave solder bath and aggressive cleaning steps. This guide shows which materials such as polyimide and aluminium hold up, what matters for adhesive and printing, and how to avoid yellowing and peeling.
View high-temperature labelsWhat stresses do PCB labels face?
In PCB manufacturing a label passes through several thermal and chemical stations. During lead-free reflow soldering per IPC/JEDEC J-STD-020 the assembly reaches a peak temperature of up to 260 °C and stays several minutes above the liquidus temperature of around 217 °C.
In wave soldering the underside briefly contacts molten solder at about 250 to 260 °C. Aqueous cleaning baths, isopropanol or solvents often follow and can attack the adhesive and print. An unsuitable label bubbles, curls, yellows or peels off completely.
- Reflow soldering: peak up to 260 °C, multiple passes possible (top and bottom side).
- Wave soldering: brief contact with solder at 250‑260 °C.
- Cleaning: aqueous media, isopropanol, solvents, sometimes ultrasonic.
- Handling: barcode and data matrix must stay readable after every step.
Which label materials withstand the heat?
Two material classes dominate for direct passage through the solder oven: polyimide (PI, known as Kapton) and aluminium. Both tolerate the reflow peak well above 260 °C without melting or deforming.
What matters for adhesive and printing?
The best carrier material is useless if the adhesive softens under heat. PCB labels use acrylic high-temperature adhesives that hold permanently up to around 260 to 300 °C and do not dissolve in cleaning baths.
For printing, thermal transfer with a resin ribbon is the standard. Pure wax or wax-resin ribbons smear under heat or are wiped off by solvents. Data matrix codes should be printed with enough contrast and quiet zone so they scan reliably after soldering.
- Adhesive: acrylic high-temperature adhesive, resistant to solvents and flux.
- Application: apply at least 24 hours before soldering so the bond fully sets.
- Print: thermal transfer with resin ribbon for smear- and chemical-resistant marks.
- Code: plan data matrix or barcode with high contrast and quiet zone.
- Placement: never over pads, vias or component-dense zones.
Frequently asked questions
Which label survives reflow soldering at 260 °C?
Labels made of white polyimide or aluminium with an acrylic high-temperature adhesive survive the lead-free reflow profile per J-STD-020 up to 260 °C without peeling or yellowing.
Why do some labels yellow in the solder oven?
Natural polyimide and paper discolour under heat. For barcodes that stay readable after several passes use specially heat-stabilised white polyimide or aluminium.
Can I use standard polyester labels?
No, PET only withstands about 150 °C. Polyester is suitable only after soldering, for marking the finished product, not for the oven pass.
Which ribbon for heat-resistant printing?
A resin ribbon in thermal transfer printing. Wax and wax-resin ribbons smear under heat or are removed by solvents.
Looking for labels for your solder processes?
We supply polyimide and aluminium labels with high-temperature adhesive and matching resin ribbons - proven for reflow, wave soldering and cleaning.
Up to 300 °C
Materials withstand the entire reflow profile.
Chemical-resistant
Resistant to flux and cleaning baths.
Stays readable
Barcode and data matrix scan reliably after soldering.
Expert advice
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